Photo Credit: Candela Boats
The National Marine Manufacturers Assn. (NMMA, Chicago, Ill., U.S.) reported in October 2020 that power boat retail sales had increased 8% year to date (YTD) compared to the same period in 2019. Sales of personal water craft (PWC), pontoons and freshwater fishing boats were up 2%, 9% and 10% respectively YTD, while sales of saltwater fishing boats, tow boats, cruisers and yachts each had double-digit growth ranging from 11% to 15%, compared to 2019. “2020 has been a banner year for new power boat retail sales, and we expect that we’ll end the year with annual boat sales reaching a 13-year high,” says Vicky Yu, NMMA director of business intelligence.
The electric-powered Seven, in foiling mode is 15 times more efficient than a comparable gas-powered planing boat. Photo Credit: Candela Boats
A growing trend in both sail and power boats is foiling— that is, the use of underwater wings known as hydrofoils to lift the hull out of the water and “fly” (see “Composites enable novel flying speedboat”). Though foiling has been around for decades, its benefits were broadcast during the 2013 America’s Cup race where both Team New Zealand and Oracle Team USA used foils to achieve sailing speeds of 40 knots/46 mph in a 17-knot breeze — considerably faster than previous America’s Cup racers at speeds of 11-13 knots (13-15 mph).
Foils are typically V-shaped blades that pierce the water’s surface or T-shaped blades that remain below the water. Some boats use a combination of both. Similar to airfoils on a plane, these generate lift so that as the boat gains speed — in most applications, 15-18 knots — its hull lifts out of the water. The foils are typically retracted at lower speeds, actuated by electronics.
Because foiling boats are raised out of the water, they have less resistance and drag, and thus are more efficient — many claim a 30-40% reduction in fuel consumption. One example is the 7.7-meter-long electric-powered Seven by Candela Boats (Lidingö, Sweden), which claims to be 4-5 times more energy efficient versus a gas-powered planing boat with a 95% lower cost of ownership. The Seven begins foiling at 14-15 knots, cruises at 22 knots, has a maximum speed of 30 knots and a range of 50 nautical miles.
Foils are typically made from carbon fiber reinforced polymer (CFRP) composites. The Seven’s foils are made from unidirectional (UD) carbon fiber tapes infused with Sicomin Epoxy Systems (Châteauneuf les Martigues, France) SR1710 epoxy resin and room-temperature cured, followed by a 40°C post-cure. The Seven’s hull is made from the same carbon fiber and epoxy, which is also a trend, because these “flying” boats have increased need for lightweight and stiffness.
A large CFRP foil vacuum-bagged onto a CFRP tool and ready to cure in an autoclave for a performance multihull sailboat (note holes for air ventilation). Photo Credit: Holland Composites
Another manufacturer of both composite foils and foiling boats is Holland Composites (Lelystad, Netherlands). Its brand DNA Performance Sailing produces high-performance foiling, sailing multihulls ranging from 5.5 to 14 meters long. “Our small boats were the first foiling catamarans in competition,” says Sven Erik Janssen, Holland Composites’ co-managing partner. The company also produces composite hydrofoils for record-setting racing yachts, and like Candela, uses carbon fiber and infusion but also autoclave-cured prepreg, depending on performance and cost requirements. “We have a technique in-house that can create really highly loaded parts without failure, and a unique one-shot production method for these very high-performance foils,” he adds.
Although costs for foiling boats are typically higher than for traditional boats, due to the extensive development and computer-aided design required, as well as lightweight materials like carbon fiber, the improved performance typically pays back the difference in as little as three years, according to some manufacturers. Another factor is that as the push for more environmentally friendly boats continues, foiling offers a means to improve the boating performance possible with electric power. “If you want to go far and fast with a battery, foiling is the only way,” says Candela Boats communications director Mikael Mahlberg, in the August 2020 Soundings Trade Only Today article, “We have liftoff.”
Continued increase in CFRP
The drive by boat owners and operators for higher speed and performance, while reducing fuel consumption and environmental impact, is slowly increasing use of CFRP in marine overall. One example is the lightweight CFRP deckhouse that Holland Composites produces for Windcat Workboats wind farm service/support vessels, which uses resin-infused CFRP foam sandwich construction for stiffness to achieve a large, open span without pillars inside the cabin.
“The monocoque deckhouse is lightweight enough that we can put it on good dampeners to isolate [it] from engine and wave vibration in the hull,” says Janssen. “Windcat is known for its really quiet ride, and the boats are well-liked by the large wind turbine OEMs. All of these wind farms must be maintained, so there is a new market for high-speed catamarans of 50 to 60 feet in length.”
The CFRP deckhouses that Holland Composites produces for Windcat Workboats catamarans enable mounting on vibration isolators for a quiet ride enjoyed by wind turbine crews. Photo Credit: Holland Composites
Another example of new, higher-performance designs, albeit much smaller, is the Tyr fishing kayak (see “Designing the ultimate stand-up fishing kayak”) by Apex Watercraft (Rock Island, Tenn., U.S.). This all-composite design uses high-impact epoxy resin from Premium Resin Tech (Port Huron, Mich., U.S.) and carbon fiber twill fabric from Firestone (Kings Mountain, N.C., U.S.) to match the light weight and high performance of racing kayaks, but with a design that’s simple to use. The 12-foot-long, 10-inch-wide Tyr features a planing hull, level with the water at one end to facilitate entry, exit and equipment loading. A planing hull is also more stable, reduces draft, enables the kayak to travel faster and is more maneuverable than typical kayak hulls.
The carbon fiber/epoxy Tyr fishing kayak promises top-of-the-line performance. Photo Credit: Apex Watercraft
The Tyr’s lightweight and stiff construction enable this design without scupper holes to drain off water that are standard for plastic kayaks, which use rounded hulls to achieve the stability necessary for standing while fishing. “Plastic kayaks would be too flimsy to hold their shape if they were designed with the hull shape of my Apex watercraft,” says company founder Eric Jackson. The Tyr also features selective use of Innegra (Greenville, S.C., U.S.) fiber in the hull to increase impact resistance and long-term durability.
3D printing moves from molds to hulls
3D printing of fiber-reinforced composite molds continues to advance. For example, Nedcam (Heerenveen, Netherlands) recently added a CEAD (Delft, Netherlands) AM Flexbot robotic 3D printer. Nedcam currently produces plugs and molds from glass fiber-reinforced composites and other materials, often for single or limited use, resulting in tons of waste every year. The company will now offer 3D printing production services to manufacturers looking for large-size applications, using optimized fiber-reinforced thermoplastic pellet materials from DSM (Geleen, Netherlands). Its goals are to reduce waste and increase sustainability. “By combining DSM’s 3D printing and thermoplastics expertise with our production knowledge and production facilities, we want to take the necessary steps toward a sustainable and fully circular model production process,” says Nedcam founder Erwin van Maaren.
Using continuous glass fiber and vinyl ester resin, moi composites 3D-printed the MAMBO in sections and then laminated them together. Photo Credit: moi composites
2020 also saw the completion of MAMBO (Motor Additive ManufacturingBOat), claimed by builder moi composites (Milan, Italy) to be the first 3D-printed boat using continuous glass fiber-reinforced thermoset composites. The 6.5-meter-long, 2.5-meter-wide power boat demonstrates a new,
unique shape that isn’t possible with traditional manufacturing. It was printed in sections using robots guided by generative algorithms that enable printing with continuous fibers direct from the digital model. The sections were then laminated together to create the final, sculpted structure without the traditional division between hull and deck.
Continuous fiber reinforcement coupled with vinyl ester resin — favored in marine applications for its long-term resistance to seawater — enables MAMBO to be strong, durable and lightweight. By creating 3D printed structures without the need for plugs or molds, it is also possible to build actual products — not just prototypes — in small lots or as unique, one-off constructions in a way that is efficient and cost-effective. Moi’s partners in the MAMBO project include digital design software supplier Autodesk (San Rafael, Calif., U.S.) and glass fiber supplier Owens Corning (Toledo, Ohio, U.S.).
More recently, Thermwood (Dale, Ind., U.S.) 3D-printed several sections of a 51-foot-long yacht hull mold on its Thermwood LSAM MT, a patented vertical layer print (VLP) technology. The demonstrator boasts carbon fiber-reinforced ABS from Techmer PM LLC (Clinton, Tenn., U.S.).
Composites in ships
FIBRESHIP hull demonstrator
Designed in composites by Technicas y Servicios de Ingeniría (TSI), this 20-tonne section of an 85-meter fishing research vessel reduces weight 70% versus steel. Photo Credit: FIBRESHIP, TSI
Another large trend is the progress being made in a wave of demonstration projects by two European consortia, FIBRESHIP and RAMSSES, supported by the 378-member European network for Lightweight Applications at Sea (E-LASS). These include composite decks, rudders, hulls, modular cabins and superstructures, patch repairs to steel and composite-to-steel welded joints (see “Removing barriers to lightweighting ships with composites”). They aim to demonstrate the fire and structural performance of large composite structures and whole vessels as well as new production methods, joining technologies, design tools and routes to certification. FIBRESHIP has completed a 20-tonne section of an 85-meter-long fishing research vessel (FRV) made using composites. Measuring 11 by 11 by 8.6 meters, it was built by iXblue shipyard in La Ciotat, France, and exhibited at FIBRESHIP’s second public workshop in June 2019.
Meanwhile, RAMSSES has 13 demonstrators in progress, 10 of which feature composites, including an all-composite, 80-meter-long, offshore patrol-type vessel. Damen Shipyard Group (Gorinchem, Netherlands) is leading demonstration of a 6-by-6-by-3-meter full-scale composite hull section of this ship, made using vacuum infusion and a novel resin by Evonik (Essen, Germany). Damen is also working with InfraCore Co. (Rotterdam, Netherlands) to apply technology used by sister company FiberCore Europe (Rotterdam) in more than 1,000 composite bridges and lock gates. InfraCore is building decks, bulkheads and hull structure for the demonstrator, which will be tested for structural and fire performance. “We will use both horizontal and vertical infusion to produce the hull section in one shot,” says InfraCore operations manager Laurent Morel. “So far, we have infused to a height of 9.8 meters.”
Composites have already been demonstrated in the first roll-on/roll-off car carrier to use a composite cargo deck, designed and built by Uljanik Group (Pula, Croatia) as part of RAMSSES work package 14 (see “Low weight on the high seas”), as well as a lightweight sundeck for a 110-meter-long river cruise ship (see “Composite deck reduces river ship draft”) and a composite tween deck for a 200-meter-long general cargo carrier. A tween deck is a removable deck to divide the cargo hold of a ship. Compocean (Sandvika, Norway), working with Oshima Shipbuilding (Nagasaki, Japan) and DNV GL, has developed a composite tween deck aimed at cutting weight by 50% versus steel. The resulting 9-by-2-meter glass fiber-reinforced prototype was tested for impact and maximum loads in 2017. Compocean has now extended this development to include ship owner Masterbulk Pte Ltd. (Singapore) and build a full-scale 27-by-12-meter prototype composite tween deck, to be installed in a ship and tested until late 2021.
Composite tween deck
Oshima Shipbuilding’s new 65k open-hatch general cargo carrier design will use Compocean’s prototype composite tween deck, which saves 50% weight vs. steel. Photo Credit: Compocean, DNV GL
Composite ship rudders are also being developed. As part of RAMSSES work package 12, Becker Marine Systems (BMS, Hamburg, Germany) is demonstrating a lightweight composite flap for a steel rudder. By adding a hinged aft flap to such rudders, which typically weigh more than 200 tons, explains Jörg Mehldau, head of R&D at BMS, “you can significantly reduce the rudder area.” BMS pioneered this flap rudder, which reduces turn radius, improves course-keeping and maneuverability and enables ship berthing without tugboat assistance. A composite flap reduces weight and enables more efficient shapes and designs. For RAMSSES, an 11.8-meter-long by 0.9-meter-wide flap with a chord of 2.9 meters has been developed as a full-scale test case aimed at one of the largest container ships (≈400 meters long).
The flap will be produced using resin infusion and a design from InfraCore, which, Mehldau explains, was the best for production flexibility, cost and structural performance. Container ship rudders must withstand loads of roughly 100 tons per square meter with a surface area of 150 square meters. Instead of bonding a high-density structural core to faceskins, InfraCore uses a low-density foam core only as a permanent formwork for multiple Z-shaped, two-flanged web structures. These are overlapped, faced with multiaxial fabrics and co-infused to form a robust construction. InfraCore will build a 1:6 scale demonstrator, using glass fiber and polyester resin already certified by DNV GL to keep costs low. Morel at InfraCore notes that the reduced-cost composite flap is cost-competitive, “because steel ship rudders are quite complicated to manufacture.” Mehldau agrees: “Together, with less maintenance and operational cost advantages, we see a successful business case.” The demonstrator was scheduled to be finished and in testing during 2020-21.
Recycling end-of-life boats
For composites to continue to grow in any market segment, increased attention must be paid to recycling and sustainability. The Rhode Island Marine Trades Association (RIMTA, Bristol, R.I., U.S.) has been leading the Rhode Island Fiberglass Vessel (Boat) Recycling Program since January 2018. The program has tested and verified a viable recycling process and organized a network of partners to address end-of-life boats in a responsible and sustainable manner. That pilot program is now being expanded to four additional U.S. states — Connecticut, Massachusetts, Maine and Washington — thanks to a $105,452 grant from the National Oceanic and Atmospheric Administration (NOAA) Marine Debris Program. Over the past two years, the Rhode Island Fiberglass Boat Recycling Program, run by RIMTA, has recycled more than 60 tons of fiberglass materials using the new process, successfully diverting old boats from landfills. The RIMTA Foundation, which is developing a sustainable financial model for fiberglass boat recycling, will use the NOAA funding to help Washington and communities
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